Merge pull request neetcode-gh#1029 from Mahim1997/dev/543_swift

543. Diameter of Binary Tree

swift/543-Diameter-of-Binary-Tree.swift

@@ -0,0 +1,40 @@
+/**
+ * Definition for a binary tree node.
+ * public class TreeNode {
+ * public var val: Int
+ * public var left: TreeNode?
+ * public var right: TreeNode?
+ * public init() { self.val = 0; self.left = nil; self.right = nil; }
+ * public init(_ val: Int) { self.val = val; self.left = nil; self.right = nil; }
+ * public init(_ val: Int, _ left: TreeNode?, _ right: TreeNode?) {
+ * self.val = val
+ * self.left = left
+ * self.right = right
+ * }
+ * }
+ */
+class Solution {
+ private var globalMaxDiameter: Int = 0
+
+ // Additionally, update the globalDiameter here
+ func getMaxDepth(_ node: TreeNode?) -> Int {
+ guard let node = node else { return 0 }
+
+ // compute for each child
+ let leftMax = getMaxDepth(node.left)
+ let rightMax = getMaxDepth(node.right)
+
+ // update diameter
+ let diameter = leftMax + rightMax
+ self.globalMaxDiameter = max(self.globalMaxDiameter, diameter)
+
+ // return max depth of 'this' node
+ return 1 + max(leftMax, rightMax) 
+ }
+
+ func diameterOfBinaryTree(_ root: TreeNode?) -> Int {
+ self.globalMaxDiameter = 0
+ getMaxDepth(root)
+ return self.globalMaxDiameter
+ }
+}